1. Field of the Invention
This invention relates generally to valves having a powered actuator, and more particularly, but not by way of limitation, to a powered actuator for a kelly valve of a rotary drilling rig for oil wells and the like.
2. Description of the Prior Art
A particular application of the present invention is for the power actuation of an upper kelly cock valve in a standard rotary drilling rig for oil wells. The kelly valve is typically a 90.degree. operating valve such as a butterfly valve or ball valve, with that 90.degree. valve member generally being located inside a cylindrical valve body. The valve body and valve member are generally known as the kelly. The kelly or kelly joint as it is sometimes called is connected below the swivel on a drilling rig and is connected to the drill string tubing. The kelly valve therefore rotates with the drill string tubing as the oil well is being drilled. The purpose of the kelly valve is to shut off the pressure from inside the drill string tubing.
Generally kelly valves of the prior art have merely had a manually operated valve member. The problem which is frequently encountered, however, is that during emergency conditions, such as when a blowout is imminent or in process, it is very dangerous to have a workman ascend the drilling derrick in order to manually shut off the kelly valve.
The present invention is directed towards a powered actuator for such a kelly valve. The primary difficulty being that the actuator must be so constructed that it allows the kelly valve to rotate within the actuator device during normal drilling operations, and at the same time provides the capability for engaging the kelly valve to actuate the valve member and close the valve when it is necessary to do so.
The present apparatus is particularly useful in deep wells deeper than 9,000 feet where the pressures encountered in the formation greatly increase the danger of blowout.
One prior art device is known which has provided a powered actuator for a kelly valve. The apparatus is manufactured by International Tool Company, Inc. and is illustrated in a brochure entitled "OIL FIELD POWER TOOLS" published by International Tool Company, Inc. That power actuated kelly valve apparatus is designated by the trademark REMO-TROL and is best illustrated on page 3 of that brochure. It is apparent upon an examination of the description of the International Tool Company, Inc. device in its brochure, that the construction of that device is very different from the present invention. The International Tool Company device uses a pair of pinion gears attached to the valve member, said pinion gears each engaging one of a pair of straight rack gears. As is apparent from the illustrations on page 3 of the brochure, the rack gears remain in contact with the pinion gears at all times regardless of the position of the valve member.